Display apparatus capable of displaying three-dimensional images have been examined for many years. According to the Greek mathematician Euclid in 280 B.C., “biocular vision is the sensation experienced when the same object is viewed at the same time by left and right eyes viewing separate images looked at from different directions”. It is therefore necessary for a function of a three-dimensional image display device to be to provide individual images to the left and right eyes with a mutual parallax.
A large number of three-dimensional image display methods have conventionally been examined as specific methods of implementing this function. These methods can be substantially divided into methods using glasses and methods that do not use glasses. Of these methods, anaglyph methods utilizing differences in color and polarizing glasses methods utilizing polarization exist as methods using glasses. However, it is basically not possible to eliminate the bothersomeness of having to wear glasses. Methods that do not use glasses have therefore been extensively examined in recent years.
Lenticular lens methods and parallax barrier methods exist as methods that do not use glasses. The lenticular lens method was invented in approximately 1910 by Ives et. Al. The parallax barrier method was conceived by Berthier in the year 1896, and verified by Ives in the year 1903.
A parallax barrier is a light blocking plate (barrier) formed with a large number of thin vertical stripe-shaped apertures extending in mutually parallel directions, i.e. formed with slits. A display panel is arranged at a rear surface of the parallax barrier. Pixels for left eye and right eye use are then repeatedly arranged at the display panel in a direction orthogonal to a lengthwise direction of the slits. The light from each pixel is therefore partially shielded while passing through the parallax barrier. Specifically, the pixels are arranged so that light from a pixel for left eye use reaches the left eye of a viewer but the light directed towards the right eye is shielded, while light from a pixel for the right eye reaches the right eye but does not reach the left eye. As a result, the light from respective pixels reaches the left and right eyes. It is therefore possible for the observer to recognize three-dimensional images.
FIG. 59 is a perspective view showing a biocular three-dimensional image display device using a parallax barrier of the related art, and FIG. 60 is a view showing an optical model for this three-dimensional image display device. As shown in FIGS. 59 and 60, a transmission type liquid crystal display panel 1021 is provided in the three-dimensional image display device of the related art, with display pixels being provided in a matrix shape at this transmission type liquid crystal display panel 1021. A left eye pixel 1043 and a right eye pixel 1044 are provided at each display pixel. The left eye pixel 1043 and the right eye pixel 1044 are defined by a light shielding section 1006. The light shielding section 1006 is arranged in order to prevent color mixing of the image and to transmit a display signal to the pixel.
A parallax barrier 1007 is provided at the front surface of the liquid crystal display panel 1021, i.e. on the observer side and a slit 1007a extending in one director is formed in the parallax barrier 1007. The slit 1007a is arranged corresponding to a pair of the left eye pixel 1043 and the right eye pixel 1044. A light source 1010 is provided at the rear surface of the liquid crystal display panel 1021.
As shown in FIG. 60, after light irradiated from the light source 1010 has passed through the left eye pixel 1043 and the right eye pixel 1044 of the transmission type liquid crystal display panel 1021, part of the light is shielded while passing through the slit 1007a of the parallax barrier 1007 and the remaining light is emitted towards respective regions of EL and ER. This means that a left eye image is inputted to the left eye 1052 and a right eye image is inputted to the right eye 1051 because the observer has their left eye 1052 positioned at the region EL and has their right eye 1051 positioned at the region ER. The viewer can therefore recognize a three-dimensional image.
When the parallax barrier method was first conceived, there was a problem that visibility was poor because the parallax barrier was arranged between the display panel and the eyes. However, with liquid crystal displays devices implemented in recent years, it has become possible to arrange the parallax barrier at the rear of the display panel, with visibility improving as a result. Such liquid crystal display devices are currently actively being examined and have recently been made into actual products (for example, refer to non-patent literature 1). The product disclosed in non-patent literature 1 is a parallax barrier type of three-dimensional image display device using a transmission type liquid crystal panel.
On the other hand, the lenticular lens method is a three-dimensional image display method that uses a lenticular lens as an optical element for implementing three-dimensional displaying. A lenticular lens is a lens with one flat surface, and with a plurality of semi-cylindrical projections (cylindrical lenses) extending in one direction formed at the other surface. Pixels displaying right eye images and pixels displaying left eye images are alternately arranged at a focal plane of this lens. One projecting section corresponds to one row of display units each comprised of one right eye pixel and one left eye pixel arranged in one direction. The light from each pixel is therefore divided in half in directions towards the left and right eyes by the lenticular lens. It is therefore possible for mutually different images to be recognized by the left and right eyes and it is possible for the observer to recognize a three-dimensional image.
FIG. 61 is a perspective view showing a biocular three-dimensional image display device using a lenticular lens of the related art, and FIG. 62 is a view showing an optical model for this three-dimensional image display device. As shown in FIGS. 61 and 62, a transmission type liquid crystal display panel 2021 is provided in the three-dimensional image display device of the related art, with display pixels being provided in a matrix shape at this transmission type liquid crystal display panel 2021. A left eye pixel 2043 and a right eye pixel 2044 are provided at each display pixel. A lenticular lens 2003 is provided at the front surface of the liquid crystal display panel 2021, i.e. on the observer side. A cylindrical lens 2003a that is a semi-cylindrical projecting section extending in one direction mutually in parallel is formed at the lenticular lens 2003. This cylindrical lens 2003a is arranged corresponding to two pixels of the transmission type liquid crystal display panel 2021, i.e. to one pair of a left eye pixel 2043 and a right eye pixel 2044. A light source 2010 is provided to the back surface side of the liquid crystal display panel 2021.
As shown in FIG. 62, after light irradiated from the light source 2010 passes through the left eye pixel 2043 and the right eye pixel 2044 of the transmission type liquid crystal display panel 2021, the light is refracted by the cylindrical lens 2003a and emitted towards the regions EL and ER. This means that a left eye image is inputted to the left eye 2052 and a right eye image is inputted to the right eye 2051 because the observer has their left eye 2052 positioned at the region EL and has their right eye 2051 positioned at the region ER. It is therefore possible for the observer to recognize three-dimensional images.
The parallax barrier method is a method where unnecessary light is “shielded” by a barrier, whereas the lenticular lens method is a method that changes the direction of travel of the light. This means that, in theory, the brightness of the display screen does not fall compared to a flat display even when displaying three-dimensionally. Application is therefore being examined in particular to terminal devices such as mobile equipment that requires both high brightness displaying and low power consumption and performance.
Simultaneous multiple image displaying devices that display a plurality of images at the same time have also been developed as other image display devices using a lenticular lens (for example, refer to patent literature 1). FIG. 63 (FIG. 10 of patent literature 1) is a schematic diagram showing a simultaneous multiple image displaying device of the related art disclosed in patent literature 1, and FIG. 64 is a diagram explaining the working of this simultaneous multiple image displaying device. As shown in FIG. 63, a simultaneous multiple image displaying device 3001 of the related art has a lenticular lens 3003 arranged at a front surface of the CRT3002.
As shown in FIG. 64, the simultaneous multiple image displaying device of the related art disclosed in patent literature 1 utilizes a function of dividing the image using the lenticular lens so as to enable images that are different for every direction of observation to be displayed at the same time under the same conditions. As a result, it is possible for a single simultaneous multiple image displaying device to simultaneously provide mutually different images to a plurality of viewers positioned in mutually different directions with respect to this display device. In patent literature 1, it is disclosed that by using this simultaneous multiple image displaying device, it is possible to reduce both footprint and electricity costs compared to the usual case where one image display devices are prepared just for the number of images wished to be displayed at the same time.
On the other hand, with terminal devices such as mobile equipment, ease of portability and length of usage time are important factors. It is therefore wished to reduce power consumption so that driving for long period of time is possible even with small, lightweight batteries that are capable of accumulating only a small amount of electrical power. Further, situations of use in extremely bright locations outdoors occur frequently. It is therefore necessary to make the brightness of the screen high every one minute in order to ensure sufficient visibility in bright locations. It is therefore preferable to use semi-transparent liquid crystal display devices as display devices satisfying such requirements.
With display devices using liquid crystal, the liquid crystal molecules themselves do not emit light. It is therefore necessary to use some kind of light in order to view the display. Typical liquid crystal display devices can be substantially divided into transmission type, reflecting type, and a semi-transmissive type display devices combining both transmitted light and reflected light, depending on the type of light source used. Low power consumption is possible with the reflecting type display devices because external light is utilized in displaying. However, display performance such as for contrast is degraded upon comparison with transmission type display devices. Transmission type and semi-transmissive type display devices therefore currently constitute the mainstream for liquid crystal displays devices. With transmission type and semi-transmissive type liquid crystal display devices, a light source device is installed at the back surface of the liquid crystal panel, with displaying then being implemented utilizing light emitted by this light source device. In particular, small and medium-sized liquid crystal display devices are carried by the observer and used in various situations. A semi-transmissive liquid crystal display device having a high degree of visibility can therefore be used in any situation by viewing a reflective display in bright locations, and viewing a transmission display in dark locations.
FIG. 65 is a plan view showing a first semi-transmissive type liquid crystal display device of the related art as disclosed in non-patent literature 2. As shown in FIG. 65, with the first liquid crystal display device of the related art, each of pixels 4040 of a semi-transmissive type liquid crystal display panel 4022 are divided into three color regions of R (red), G (green), and B (blue). Each color region is then divided into a transmission region and a reflective region. That is, the pixel 4040 is divided into six regions of a transmission region (red) 4041R, a reflective region (red) 4042R, a transmission region (green) 4041G, a reflective region (green) 4042G, a transmission region (blue) 4041B, and a reflective region (blue) 4042B. The semi-transmissive type liquid crystal display device of the related art disclosed in non-patent literature 2 is a display device capable of implementing both reflective displaying and transmission displaying and is not a three-dimensional image display device or a simultaneous multiple image displaying device. A lenticular lens or parallax barrier etc. are therefore not provided.
With the first semi-transmissive type liquid crystal display device of the related art, a metal film (not shown) is formed at the surface of the side contacting the liquid crystal of the glass substrate of the rear side, of two sheets of glass substrate of the semi-transmissive type liquid crystal display panel 4022 at each reflective region. This metal film then reflects external light. As a result, at the transmission region, light from the light source (not shown) is transmitted through the liquid crystal layer of the liquid crystal panel (not shown) and an image is formed. Further, at the reflective region, external light such as natural light and illuminating light within a room is transmitted through the liquid crystal layer. This light is then reflected by the metal film and is again transmitted through the liquid crystal layer so as to form an image. It is therefore possible to utilize external light as part of the light source at locations where the external light is very bright. As a result, upon comparison with the transmission type liquid crystal display device, the semi-transmissive type liquid crystal display device is capable of suppressing power consumption required to maintain brightness of the display screen and illuminate the light source.
With this semi-transmissive type liquid crystal display device, it is one time light from a backlight is transmitted at the color filter layer corresponding to a transmission section; while the external light is transmitted two times, once when incident, and once when emitted, at a color filter layer corresponding to a reflective section. When the color filter layer is similarly arranged at the transmission section and the reflective section, there is a problem that the transmissivity of the reflective section falls and the color of the display becomes denser. Technology is therefore proposed where a region corresponding to the reflective section is configured from a region where a color filter layer is formed and a region where a color filter layer is not formed.
FIG. 66 is a plan view showing a second semi-transmissive type liquid crystal display device of the related art as disclosed in non-patent literature 2. As shown in FIG. 66, the second semi-transmissive type liquid crystal display device of the related art includes a reflective electrode 5003 and a transparent electrode 5008 formed in prescribed shapes on a lower side substrate 5001 and includes a color filter layer 5011 formed on a color filter substrate arranged facing the lower side substrate 5001. A signal electrode 5021 for driving the electrodes, a scanning electrode 5022, and a thin-film transistor (TFT) 5023 arranged in the vicinity of an intersecting section of the two types of electrodes are formed at the periphery of the reflective electrode 5003 and the transparent electrode 5008. Further, the color filter layer 5001 includes three types of filter layer, a red color filter layer 5001a, a green color filter layer 5011b, and a blue color filter 5011c. Each color filter layer of each respective color is formed so as not to overlap with the whole of the reflective electrode 5003 but to always overlap with the whole of the transmission electrode 5008. That is, a region is formed where the whole of the transparent electrode 5008 is covered by the color filter layer 5011, whereas the reflective electrode 5003 is not covered by the color filter layer 5011.
With the second semi-transmissive type liquid crystal display device of the related art, a region is provided where the color filter layer is not formed at the reflective section. The problem where the color for reflective displaying becomes darker than for transmission displaying is therefore suppressed by displaying white at the region where the color filter layer is not formed and mixing colors with light that is transmitted through the color filter layer. It is therefore possible to implement bright reflective displaying.
Non-patent literature 1: Nikkei Electronics No. 838, Jan. 6, 2003, p. 26-27 (table 1)
Non-patent literature 2: Nikkei microelectronics supplement “flat panel display”, Nikkei BP p. 108-113 (FIG. 4)
Patent literature 1: Unexamined Japanese Patent Application KOKAI Publication No. 06-332354 (FIG. 9, FIG. 10)
Patent literature 2: Unexamined Japanese Patent Application KOKAI Publication No. 2000-111902 (FIG. 1)